Clean air or electric lights? That could be the debate if carbon policies are implemented too far in advance of new technologies, a new study warns.

In a survey conducted by the North American Electric Reliability Corporation (NERC), several utility executives have begun to express fears that the cancellation of coal-fired power plants and the implementation of carbon reduction policies could make it difficult to deliver power in some regions.

Carbon policies will have to take into account the problems that will come with switching over from a coal infrastructure. The power grid will also have to be upgraded to allow electricity to be consumed more efficiently.

In many ways, it's a question of math. Coal provides about 49 percent of the electric power in the U.S. and in some regions coal provides the bulk of the power. Thirty gigawatts of coal plants were deferred or cancelled between 2002 and 2007, while 3.5 gigawatts of coal plants were scuttled in the first half of 2008 alone, according to the study.

Renewable power and cleaner forms of fossil fuels are arriving to fill a good portion of the void. NERC, for instance, increased its forecast for new natural gas capacity by 20 gigawatts from a year ago. Besides emitting fewer greenhouse gases, natural gas plants are quicker and easier to construct, the study said.

Nonetheless, demand for power keeps increasing and a mismatch between supply and demand could mean lights out in some places. Increased demand could also crimp the supplies of natural gas. (Russia, Iran and Qatar have the largest national natural gas reserves.)

"We are concerned about grid reliability in the next five to ten years because of coal power plant cancellations," said Pat Williams, director of engineering at East Mississippi Electric Power, according to the study.

"If timetables for reductions are too short, new technologies may not be available to prevent massive fuel switching from coal to natural gas. And, if such fuel switching were to occur quickly, the bulk electric system would be unable to accommodate relocated generating facilities, which, in turn, would have an adverse impact on system reliability," said Dan Steen, vice president of environmental at FirstEnergy Service Company in Ohio, according to the study.

Clean coal technologies could help ameliorate the situation, but these technologies will have to become viable commercially before 2025 to help out. Clean coal technologies also consume energy. Some companies, for instance, turn coal into a gas and then burn it like natural gas. In turn, of course, that means burning even more coal. Some experts say as much as 320 gigawatts would have to be erected just to compensate for parasitic losses.

A better grid will also be required. The grid was not created with the idea of swapping power on a nationwide basis. Delivering power to customers, regardless of where it's implemented will be crucial to efficient use.

It will also be important for the growth of renewables. The potential for solar and wind power is simply not high enough in some regions to meet renewable power portfolios in some regions. Thus, those areas will have to get renewable power from somewhere else.

"The success of climate change initiatives will depend on successful and aggressive regional planning," said James Hoecker, Counsel for WIRES, a trade group, in the report.